With consumer drones exploding in popularity, a Virginia-based start-up is aiming to help citizens, governments and corporations detect when unwanted drones are near.

Drones are everywhere in America these days, from sports arenas to movie sets — even the White House lawn. It's clear they've gone mainstream, but the reality is, they're not always welcome.

DroneShield is a start-up trying to change that. The company, based in Herndon, Virginia, has developed technology to detect consumer quadcopters and multicopters. It was launched in 2014 by two former defense contractors, John Franklin and Brian Hearing, after they saw an explosion in the use of consumer drones.

"We thought that if people are concerned about privacy, the thing they should really be concerned about are these smaller consumer models," said co-founder and CTO Franklin. "It used to be enough to protect something with a fence — metal detectors, barricades, that sort of thing. But nowadays anyone can go out for several hundred dollars and be a few blocks away and fly right over that fence."

They've raised just over $1 million in funding and have sold about 300 units so far, which begin pricing at $2,000. They offer two sensors right now — one long- and one short range. Clients range from individuals to major corporations; government agencies and sporting arenas also rely on DroneShield's detection technology.

Daniel Acker | Bloomberg | Getty Images

The company's technology is based on acoustics — the sensors are long metal rods that stand upright with microphones attached to them. "It's very simple; it's a microphone that's recording ambient noise. We take that sound and process it using algorithms that compare it to known drone signatures. When we detect a drone, we issue an alert to the end user, typically via email or a text message," said Franklin.

The next step is where things get tricky for users, Franklin said, because right now there's little recourse that individuals can take against drones.

"It's almost in all cases illegal to take action against a drone that's flying in a public airspace," he said. "Law enforcement has other recourse, but a private citizen can't do a lot of jam or shoot at drones without running afoul of the law."

He added that you always have to be aware that in taking countermeasures against drones, there is often collateral damage. "If you're a big Fortune 100 or 500 company and you're trying to protect a corporate campus and you detect and take down a drone and it lands in the highway during rush hour, you have to always be cognizant of those kinds of consequences."

Initially, exporting the product was a challenge, as Franklin said it took a long time to get the government to acknowledge that the product was not military technology.

"For the first six months, we had to turn down every foreign inquiry," he said, adding that today 80 percent of their business is from outside the U.S.

And if the regulatory environment eases up, DroneShield may be doing more than just detecting acoustics in the future.

"We are focused on getting a solid customer base and maybe expanding the technology into other detection methods," he said.

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